Addition agent for lubricating oil and method of making same



Patented July 11, 944

ADDITION AGENT FOR LUBRIOATING OIL AND METHOD OF MAKING SAME Felix C.Glemski, Philadelphia. Pa.. aseignor to The Atlantic Refining Company,Philadelphia, Pa... a corporation of Pennsylvania No Drawing. Originalapplication February 20,

1940, Serial No. 319,841. Divided and this application December 7, 1940,Serial No. 389,130

4 Claims. (01. 260-461) This invention relates to the treatment ofhydrocarbon products such as mineral oils to improve theircharacteristics, and particularly'to the addition topetroleumfilubricating. oils of certain materials which'improve theirability to resist the deteriorating eflectof oxidation and their abilityto lubricate bearing surfaces which are subjected to extreme pressuressuch as are now commonly encountered in the newer types of machinery.

This application is a division of my application Serial No. 319,841,filed February 20, 1940, en-

titled Lubricant.

Moderately refined oils, such as motor oils and other moderately refinedlubricating oils and moderately refined turbine oils normally used underconditions of exposure to oxidation in the presence of metals, oxidize,giving rise to sludge or acidic oxidation products, or a combinationthereof as the case may be, frequently corrosive to the metals whichthey encounter in use, as for example bearing metals in automotive use,and copper and copper alloys in turbine use. It has now been found thatstabilization of these oils against such oxidation effects may beconveniently accomplished by addition to the oils of certain materialswhich substantially retard the These changes in engine design have beenconcurrent with marked advances in methods of refining lubricant oilsfor automotive use. demand for oils having lesser changes in viscositywith temperature change; i. e., higher viscosity index (frequentlydesignated as V. I.), has been met by refining lubricants intended formotor oils by certain solvent refining or solvent extraction processes,wherein advantage is taken of the 'selective solvent power forhydrocarbons of various types which is possessed by certain liquidreagents, for example, dichlorodiethylether, cresylic acid, phenol,chloraniline, chlorophenol, pheoxidation of the oils, whether or notmetal is present, and which apparently have the ability to inhibit thecatalytic effectof metals in promoting oxidation reactions and thusprevent the formation of sludge or acidic constituents and the like, ora combination thereof as the case may be, under normal conditions ofuse.

Recent changes in automotive engine design, tending toward higherbearing pressures, higher rotative speeds, higher engine temperatures,and the like, have occasioned departure from the use of the usualbearing metals such as babbitt. Thenewer bearing metals are of diflerentnature than those less recently developed and while harder, are ingeneral more susceptible to destructive agencies of a corrosive nature.Typical of these newer bearings are those composed of a cadmium-silveralloy supported upon a steel back, which are now widely installed incertain makes of automobiles. Others of these relatively new bearingmetals which may, be mentioned are copper-lead alloys, copper-lead-tinalloys, cadmium-nickel alloys, cadmium-zinc alloys, cadmium-zinc alloysmodified by the presence of lead, antimony, or both,and a general classof alloys consisting mainly of lead and hardened with calcium, barium,potassium, antimony, and the like, known generically as high leadbabbittsi iii) netidine, benzyl alcohol, nitrobenzene, benzonitrile,furfural, aniline, benzyl acetate, liquid sulphur dioxide, mixtures ofliquid sulphurdioxide or aniline with benzol, and the like. Thosesolvent refining processes are designed to concentrate in the desiredlubricant fraction those compounds of a paraillnic nature possessed ofthe ability'to suffer only a small change of viscosity .with'change oftemperature, and to reject the compounds of naphthenic nature which dosuffer such change of viscosity to such a marked degree. These refiningprocesses have provided a supply of oil of quite desirable generalcharacteristics definitely far superior to any oil previously producedfrom mixed base or asphaltic' crudes. and superior to a like, thoughlesser, degr'ee over oils previously produced from paraflln base crudes.

It has been found that the solvent refined motor oils referred to aboveare definitely corrosive to the newer bearing metals referred to aboveunder extreme conditions of automotive use, due to oxidation during use,sometimes resulting in bearing failure after only a few thousand milesof driving. Difliculties are frequently encountered due to hearing'corrosion in automotive equipment operated at sustained high speeds ofthe order of to M. P. H., or under other conditions conducive to highcrankcase temperatures of the order of 275 F. or higher. It is furtherknown that the same'reaction, viz., corrosion' of alloy bearingmetalssuch as cadmiumthe problem is encountered in oils having a V. I.

of or higher, particularly at elevated temperatures of engine operation.

Furthermore, the present trend in automotive design toward lower bodystyles, rapid accelera- The ' tion, and the use of hypoid gears hasincreased theunit loadi'ngs'qn rear axles. In some cases the unitpressures encountered become great enough to rupture the oil film ofordinary mineral oil lubricants, with consequent metal to metal contact.In other lines of power transmission and the like,'there is a similartendency toward the use of high unit pressures of a degree which arenear or beyond the limit at which mineral oils, alone, will maintaineflective lubrication. This invention is therefore specificallyconcerned with the production of lubricants capable of 'withstanding thehigh unit loadings which occur in such instances. Such lubricants aregenerally spoken of as extreme pressure lubricants.

Extreme pressure lubricants are normally prothread by adding to ahydrocarbon lubricant a small amount of some characterizing substancewhich enables it to maintain a lubricant film unruptured underconditions which would cause the breakdown of a fllm formed of oil.alone.

Such additive substances are spoken of as E. P. (extreme pressure)bases, or- E. P. ingredients. Many commonly used E. P. bases arecomposed oi sulphur-dissolved in mineral oil, sulphurized vegetable oranimal oils, chlorinated compounds, metallic soaps, and the like.Thisinventi'on is specifically concerned with the use, as E. P.characterizlng ingredients, of compounds new and novel for this purpose,and not heretofore so used or known to be useful for this purpose.

It is an object of this invention to provide an extreme pressurelubricant, which lubricant is superior to lubricants of this classheretofore commonly known, particularly in load-carrying capacity.stability, and maintenance of extreme pressure lubricating propertiesunder sustained conditions of high loading. It is an object of thisinvention to prepare novel and valuable ingredients and to combine themwith hydrocarbon lubricant oils to produce lubricants having high loadbearing capabilities. to prepare such ingredients which have goodcharacteristics of stability, which are less corrosive, and which imparta greater influence when present in much smaller amounts than arerequired with extreme pressure ingredients now commercially available.Further objects are the provision of methods of making the ingredient oringredients, methods of preparing lubricants containing these novelcharacterizing ingredients, and methods of lubrication making use of thelubricants so produced.

It is an important object of this invention to provide means forsatisfactorily inhibiting or preventing corrosion from taking place to aserious degree particularly in oils of relatively high-viscosity index.It is also an object oi this invention to alter or modify a highlyrefined motor oil, normally corrosiv bythe use of an additive ingredientcapable oi' substantially inhibiting this corrosion. It is anirther'obiect of this invention to provide a substantiallynon-corrosive motor oil tion is to provide an additive. reagent oringredient capable-of inhibiting the corrosive propas trimethylphosphite,

assaess l in internal combustion engines, which do not deposit gummy orresinous films or "lacquers" upon pistons, rings, valves, and cylinderwalls of engines, and especially those operated at relatively hightemperatures or for long periods of time, or a combination thereof asthe case may be.

I have found that hydrocarbon oils of the classes defined above can bestabilized against the formation of acidic or corrosive or sludgebodies, or a combination thereof as the case may be, by the addition tosaid oils of a relatively small amount of a substantially stable,oil-soluble, water-insoluble reaction product of an ester of phosphorousacid and a relatively high boiling aliphatic alcohol. I have also foundthat novel lubricants having extreme pressure lubricatingcharacteristics can be produced by adding to oil a suflicient quantityof said reaction product. Among the esters of phosphorous acid which maybe suitably employed in the production of my reaction products are thearyl phosphites such as triphenyl phosphite, trinaphthyl phosphite,trianthryl phosphite; the alkylated aryl phosphites such as thetricresyl phosphites, trixylenyl phosphites, triethyl phenyl phosphites,tripropyl phenyl phosphites, tributyl phenyl phosphites, trlamyl phenylphosphites, and the isomers and higher homophosphites in the productionoimy reaction products, I may also utilize th alkyl phosphites suchiethyl phosphite, tributyl phosphite, and triamyl phosphite. Mixedalkyl-aryl phosphites and hydro-aromatic phosphites, as well as aryl oralkyl mono and diphosphites and the esters of hypophosphorous,pyrophosphorous, and thiophosphorous acids may also be employed.

The relatively high boiling aliphatic alcohols which I utilize intheipreparation of'my reaction 'of highv. I. Still another object ofthis invenerties of these oils. The production of solvent productsinclude the Imono and polyhydric alcohols, preferably those havingboiling points above about 200 C. Representative examples of suchcompounds are octyl alcohol, nonyl alcohol, decyl alcohol, undecyl orlauryl alcohol, oleyl alcohol, stearyl alcohol, ceryl alcohol, ethyleneglycol, propylene glycol, butylene glycol, diethylene glycol,triethylene glycol, and glycerol. I may likewise employ high boilingether alcohols such as diethylene glycol monoethyl ether, diethyleneglycol monobutyl ether, and the like.

The above mentioned substantially stable oilsoluble, water-insolublereaction products are said oils against the accelerating action ofmetals. on the deteriorating effects or oxidationreactions under normalconditions oi use or handling or in reparing the reaction product to beem-' played in accordance with my invention, 1 pro for to a the esterofphosphorous acid with the relatively high boiling alcohol andthereafter bring the mixture to a temperature suficient to causereaction of the ingredients, whereby there is introduced into the esterof phosphorous acid at least one high boiling alcohol group. The molratio of ester to alcohol employed may vary from 1:1 to 1:25, and ispreferably of the order of about 121.4. The admixture of ester andalcohol may be heated at atmospheric pressure under a reflux condenserto a temperature suillcient to eflect reaction, for example,temperatures oi. the order of from 200 F. to 500 F., and the re-,

sulting oil-soluble, water-insoluble reaction product may be separatedfrom the byproducts of the reaction by distillation under reducedpressure, or by recrystallization from asuitable solvent, or by washingwith a solvent having selective solvent power for either the reactionproduct or the undesirable byproducts. Or, if both the ester I and thealcohol are relatively high boiling, the

reaction may be carried on at elevated temperatures of the order ofirom200 F. to 350 F., under reduced pressures of the order of m. m. or less.On the other hand, if the ester is relatively low boiling and thealcohol is relatively high boiling, the reaction may be carried on atelevated temperature and under a suitable superatmospheric pressure.Depending upon the ratio of ester to alcohol employed, and upon thetemperature and time of reaction, at least one and in some instances twoalcoholic groups may be introduced into the ester'oi' phosphorous acid.The reaction products so produced may be regarded as complex esters ofphosphorous acid which may or may not contain unreacted high boilingalcohol. Such reaction products have a wider range or utility andeflectiveness as inhibitors and the like than the simple esters fromwhich they are prepared.

Alternatively, my reaction product may be produced directly inhydrocarbon. oil by adding thereto suitable quantities of ester and highboiling alcohol, and then heating the mixture to a temperaturesuflicient to cause the reaction of the ester with the. alcohol,undesirable byproducts of the reaction being removed by distillation orby washing with a suitable solvent.

The reaction products produced in accordance with my invention maybeadded to hydrocarbon oils invarying amounts, depending upon thequalities it is desired to impart to the oil. For example, in order toinhibit oxidation of hydrocarbon oils such as lubricating oil, turbineoil, or electrical insulating oil such as transformer or cable 011, Imay incorporate in the oil from 0.05 per cent to 0.5 per cent of myreaction products. In the case of lubricating oils for internalcombustion engines, quantities of reaction product of the order oi 0.1per cent to 0.7 per cent willinhibit the formation of color bodies andacidity, and will inhibit corrosion of hairing metals such ascadmium-silver and copperlead alloys. My reaction products, whenemployed in quantities of the order of 0.4 per cent to 0.7 per cent,will inhibit the formation of sludge, resinous bodies, or "lacquers, andwill impart to the oils moderatedegree of film strength or extremepressure characteristics.

Where a considerable degree or improvement in film strength or extremepressure characteristics is required, my products may be employed inamounts of the order of 1 per cent to 2 per cent, or more. In thosecases where it is desirable, from an economic point of view, to employonly sufllcient quantities of my reaction products to degree of filmstrength by the addition of other agents, I may add to the oil, forexample, 0.4

per cent of my reaction products and 0.6 per cent of a film strengthagent such as tricresyl phosphate. Other film strength agents, ofcourse. may be employed in lieu of or in addition to tricresylphosphate, and the quantities of such agents may be varied as desired.

My invention may be further illustrated by the following examples,which, however, are not intended as limiting the scope thereof.

1 mol of tricresyl phosphite and 1.3 mol oi! cetyl alcohol were admixedand introduced into a vacuum still. Heat was applied to the still andthe admixture was brought to a temperature of about 150 F., whereuponthe pressure within the still was reduced to about 5 m. m. by means of avacuum pump connected to the condensing system associated with thestill. The admixture was then heated, under the reduced pressureaforesaid, to a temperature of the order of about 240 F., at whichtemperature reaction between the tricresyl phosphite and the cetylalcohol was initiated. The temperature of the reaction mixture was thenprogressively raised to about 340 F. and the mixture was maintained atsuch temperature until substantially all of the cresol liberated duringthe reaction (about 1 mol of cresol or 30.7 per cent by weight of thetricresyl phosphite initially charged) has been distilled from thereaction mixture. Traces of residual cresol may be removed from theheated reaction mixture, while under reduced pressure, by bubbling asmall quantity of air or inert gas such as carbon dioxide or nitrogenthrough the reaction mixture. mixture may be condensed and disposed ofas desired. The reaction product obtained by the above-process appearsto be a complex ester of phosphorous acid containing at least one cetylalcohol group.

The inhibiting effect of the above described reaction product upon theformation of sludge due to oxidation of lubricating oil is illustratedby the data presented in the following table. The

remove adhering oiL'and dried to constant weight. The amount of sludgeis reported as milligrams per 10 grams of oil. The oil emplayed was asolvent refined S. A. E. 20 motor oil having a Saybolt Universalviscosity 01 313 seconds at F. and an A. P. I. gravity of 293.

Oil composition Mgs. sludge Blunkoil.. 197 Blank oil+0.i% by vol. ofreaction product 99 Blank oil+0.3% by vol. of reaction product. 78 Blankoil+0.7/,, by vol. of reaction product. 59 Blank oil+l.5% by vol. ofreaction product. 42

To demonstrate the inhibiting action of my reaction product uponcorrosion of bearing metals by refined lubricating oil, the followingdata is presented. The test utilized comprised submerging in the oilsamples to be tested a weighed cadmium-silver bearing, and heating thesamples at a temperature of 340 F. for 24 The cresol distilled from the4' assaass v hours while bubbling air through the samples test oilsbeing withdrawn and examined at 8 at the rate or 3 liters per hour. Atthe comhour intervals. The results of the Chevrolet pletion of theheating period the bearings were engine tests are presented in thefollowing table.

on 0.7 reaction rod. (used) on Oil (used) hours hours 9 Properties (now)a 10 a a2 s 16 24 a2 A.P.I vi new" use 25.2 26.1 s. U. vi: A003 an an41s 4411 an ass 437 471 500 s U as as 61 as so s4 .02 2.0 as 4.9 as 1.62.8 4.1 4.1 .01 .42 '.83 .95 1.08 .as .59 .33 .91 .00 -11 .22 .42 .85.18 .06 .18 .16 .oo .10 .07 .23 .18 .03 09 .05 .19 e, 002 2,677

removed from the oil samples, washed, dried and weighed. The loss inweight, due to corrosion, is reported in milligrams. The oil employed inthis test was a selective solvent refined oil having a Saybolt Universalviscosity of 313 seconds at 100 F., and an A. P. I. gravity of Theeiiectiveness of my reaction product in increasing the film strength orload-bearing capacity of lubricating oil is illustrated by the resultstabulated below. The blank oil and the oils containing variouspercentages oi my reaction product were tested in an Almen extremepressure lubrlcant'testing machine operated at 200 R. P. M. Thepressures are expressed as lbs. per sq. in. projected bearing areasustained before seizure of the test bearing. The lubri-' eating oilemployed was the same as used in the preceding test icr'corrosioninhibition.

From-the results of the tests above set forth, it will be apparent thatin all respects the oils containing small amounts of my reaction productare markedly superior to oils to which no reaction product has beenadded.

Oil composition Film strength LbL/eq. in. Blank oil 4,000 Blank oil+0.3by vol. oi raaction product 12,000 Blank oil+1.li o by vol. of reactionproduct 17,000

To iurther demonstrate the eflectiveness of my novel reaction product,under actual conditions or use, tests were made employing a Chevroletengine. The Chevrolet engine was run for 32hours at'3,000 R. P. M.. at acranlrcase oil temperature oi 280 F., samples of the The reactionproduct of my invention may be utilized not only as an inhibitor or filmstrength agent for hydrocarbon oils, but also for similar purposes inother products such as thickened oils or greases, cutting oils,petrolatums, waxes, animal and vegetable oils, or mixtures thereof withhydrocarbon oils.

What 'I claim is:

1; The method of, producing an addition agent for hydrocarbon oils,which comprises reacting an ester of phosphorous acid with a relativelyhigh boiling aliphatic 111001101 at such temperature and for such periodof time as to introduce into said ester at least one high boilingaliphatic alcohol group.

2. The method of producing an addition agent for hydrocarbon oils, whichcomprises reacting an aryl ester of phosphorous acid with a'relativelyhigh boiling aliphatic alcohol at such temperature and for such periodof time as to introduce into said ester at least one high boilingaliphatic alcohol group.

3. The method of producing-an addition agent for hydrocarbon oils, whichcomprises heating an aryl ester of phosphorous acid with a relativelyhigh boiling aliphatic alcohol at a temperature within the range of from200 F. to

- phorous acid with from 1 to 2.5 mols of a relatively high boilingaliphatic alcohol at a temperature within the range or from 200' F. to500 F.. or a period of time suflicient to introduce into said ester atleast one high boiling aliphatic alcohol group.

FELIX C. GZEMSKI.

